feat(opentelemetry): otel metrics

changelog/unreleased/kong/otel-metrics.yml

@@ -0,0 +1,3 @@
+message: "**OpenTelemetry:** Added support for OpenTelemetry metrics."
+type: feature
+scope: Plugin

kong-3.9.0-0.rockspec

@@ -594,6 +594,7 @@ build = {
     ["kong.plugins.opentelemetry.otlp"]  = "kong/plugins/opentelemetry/otlp.lua",
     ["kong.plugins.opentelemetry.traces"] = "kong/plugins/opentelemetry/traces.lua",
     ["kong.plugins.opentelemetry.logs"] = "kong/plugins/opentelemetry/logs.lua",
+    ["kong.plugins.opentelemetry.metrics"] = "kong/plugins/opentelemetry/metrics.lua",
     ["kong.plugins.opentelemetry.utils"] = "kong/plugins/opentelemetry/utils.lua",
 
     ["kong.plugins.ai-proxy.handler"] = "kong/plugins/ai-proxy/handler.lua",

kong/clustering/compat/removed_fields.lua

@@ -166,6 +166,7 @@ return {
     opentelemetry = {
       "traces_endpoint",
       "logs_endpoint",
+      "metrics_endpoint",
       "queue.concurrency_limit",
     },
     ai_proxy = {

kong/include/opentelemetry/proto/collector/metrics/v1/metrics_service.proto

@@ -0,0 +1,79 @@
+// Copyright 2019, OpenTelemetry Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package opentelemetry.proto.collector.metrics.v1;
+
+import "opentelemetry/proto/metrics/v1/metrics.proto";
+
+option csharp_namespace = "OpenTelemetry.Proto.Collector.Metrics.V1";
+option java_multiple_files = true;
+option java_package = "io.opentelemetry.proto.collector.metrics.v1";
+option java_outer_classname = "MetricsServiceProto";
+option go_package = "go.opentelemetry.io/proto/otlp/collector/metrics/v1";
+
+// Service that can be used to push metrics between one Application
+// instrumented with OpenTelemetry and a collector, or between a collector and a
+// central collector.
+service MetricsService {
+  // For performance reasons, it is recommended to keep this RPC
+  // alive for the entire life of the application.
+  rpc Export(ExportMetricsServiceRequest) returns (ExportMetricsServiceResponse) {}
+}
+
+message ExportMetricsServiceRequest {
+  // An array of ResourceMetrics.
+  // For data coming from a single resource this array will typically contain one
+  // element. Intermediary nodes (such as OpenTelemetry Collector) that receive
+  // data from multiple origins typically batch the data before forwarding further and
+  // in that case this array will contain multiple elements.
+  repeated opentelemetry.proto.metrics.v1.ResourceMetrics resource_metrics = 1;
+}
+
+message ExportMetricsServiceResponse {
+  // The details of a partially successful export request.
+  //
+  // If the request is only partially accepted
+  // (i.e. when the server accepts only parts of the data and rejects the rest)
+  // the server MUST initialize the `partial_success` field and MUST
+  // set the `rejected_<signal>` with the number of items it rejected.
+  //
+  // Servers MAY also make use of the `partial_success` field to convey
+  // warnings/suggestions to senders even when the request was fully accepted.
+  // In such cases, the `rejected_<signal>` MUST have a value of `0` and
+  // the `error_message` MUST be non-empty.
+  //
+  // A `partial_success` message with an empty value (rejected_<signal> = 0 and
+  // `error_message` = "") is equivalent to it not being set/present. Senders
+  // SHOULD interpret it the same way as in the full success case.
+  ExportMetricsPartialSuccess partial_success = 1;
+}
+
+message ExportMetricsPartialSuccess {
+  // The number of rejected data points.
+  //
+  // A `rejected_<signal>` field holding a `0` value indicates that the
+  // request was fully accepted.
+  int64 rejected_data_points = 1;
+
+  // A developer-facing human-readable message in English. It should be used
+  // either to explain why the server rejected parts of the data during a partial
+  // success or to convey warnings/suggestions during a full success. The message
+  // should offer guidance on how users can address such issues.
+  //
+  // error_message is an optional field. An error_message with an empty value
+  // is equivalent to it not being set.
+  string error_message = 2;
+}